Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Rick Scofield]

So where and at what time is this comparison taking place?  I may be able to get away from the my part of the east bay and add my ears to the collective bunch.

Always good to meet more Labsters too.  Last time for me was Bink's Amplifier Shootout way back when at the Expression Center.

Let me know,

Rick

[John Roberts {JR}]

Pascal Pincosy wrote on Tue, 09 October 2007 18:38

Thanks for all the suggestions folks! I'm not wanting to blow any drivers with our testing, so I don't expect that we'll be hitting the clip lights much, if at all. Some of the amps we're testing are  quite stout, and it certainly wouldn't be fair to be hitting the limiting on one amplifier while another is at -10dB, now would it? I'm certainly expecting that there won't be much, if any difference between amps on the full-range testing. But going with my previous experiences, I expect there will be a real difference between the amps on subs. Hopefully we'll have enough attendees to establish  a "statistical significance."

Sounds good. I am interested in hearing your results since IMO most sub & amp  listening test differences typically involve clipping. Keeping everything linear should sound, um linear.  If the subs and source goes real low confirm adequate LF response of amps.

Statistical significance is a bit more complicated than number of participants and/or trials, but surely more is better.

Have fun

JR

[Pascal Pincosy]

Rick- PM sent

[Pascal Pincosy]

The listening test was a very interesting exercise. We did the testing at JK Sound in San Francisco. Due to some technical difficulties, the Bassmaxx subs did not attend, so the testing was limited to a SB-750 on subs, and a LA-325 for the full-range test. Amps in attendance were the Dynacord PowerH 5000, QSC PL 380, Camco Vortex 6, Crest Pro 9200, Lab Gruppen FP 10000Q, Powersoft K6, and a QSC RMX 4050HD for good measure. All the amps were power-matched with a Fluke 337 meter. Listening levels were moderate, only one channel/speaker were used, power was provided by multiple 30 amp circuits, and none of the amps got anywhere near clip during the testing. Music for the testing was Gregory Isaacs "Night Nurse" and an unidentified tech-house track.

We started the testing with the sub. Each amp was given an identifier (amp 1, amp 2, etc) but the identities were known only to me, the "switcher". We started with a pair and switched back and forth, then moving on to the next pair etc. The group of 4 listeners discussed their opinions on each amp and made notes. We then moved back and forth between amps that the listeners wanted to hear again, and opinions were a bit more cemented. There was a definite winner here, and it's not the amp you'd expect to win at all. The Crest Pro 9200 was roundly preferred over any other amp in the testing. The Powersoft K6 took a close second.

And here's where it got interesting. Dropping the naming convention, I would pick 2 different amps and have the listeners tell me if they preferred 'amp A' or 'amp B'. While the Pro 9200 could still be picked out from the rest of the amps, for the most part, even the amp decried as the worst in the initial testing phase was tied with some of the other front-runners in the second phase of tests.

Moving on to the full-range testing, we went back to the amp naming convention, but I changed the numbering to confuse any potential preferences based on the sub tests. In this phase of the tests the Camco Vortex 6 was voted the cleanest sound, with the QSC RMX 4050HD and the Dynacord PowerH 5000 close behind. Unfortunately, at this point it started getting really cold and we had to call an end to the testing.

What did we learn from these tests? Very little except that all these amps sound really good. Early on in the testing I realized that to get a meaningful and valid result, that we'd need to spend many more hours, if not days, going over a much more limited number of amps, with a much larger selection of music, in order to find meaningful results. John Frigaard, one of the attendees, put it well: "As for what we can glean from this get together, I'm still trying to put substance to it.  Maybe most importantly what we've learned is that our methodology, although attempting to be 'accurate and fair', (and for what it was, I think it was), was woefully lacking for any conclusive separation of chaff from grain.  There really was no chaff wafting from those speakers."

That being said, if you're attempting to find the highest fidelity amplifier to go with your EAW LA325's in order to play "Night Nurse" to its fullest potential, I'd suggest going with a Camco Vortex 6 on the tops, and a Crest Pro 9200 on the subs (as long as the sub is a SB750.)

So is JR right that there's no difference in sound quality between these amps when they're not in clip or power-limited? The best answer I could give would be "maybe", though in the sub testing, the listeners could pick out the 9200 from any of the others...

Were I to do this sort of test again, I would do so with the specific model of speaker I was trying to build a system for, and listen with the type of music I was planning on running on the system. I would reserve a week, and test for no more than one hour at a time. I would also test the amps much closer to their limits, since this is where they're more likely to be used most of the time. Who really cares if one amp sounds better than another or not at low volumes? Much more likely that the amps will be pushed hard during regular use. That's where the differences will really shine, and that's where I'd be looking for a quality sound.

If all this testing was too much work for the project, I would simply buy based on feature-set and price. There are many areas where effort could be better spent on a project in order to improve the sound quality than which amp sounded best on certain speakers.

[Randy Frierson]

I appreciate you going to the effort to do this..i'd like a little more info as how did the new PL380 do? Years ago i used to say the Nexo S2's sounded the best on MA5000's and it was because the distortion was just right for the sub push but as i got educated i wanted more accuracy in the sub area and that was one of the deciding factors to go the Camco Vortex way..I also noticed early on though the V-6 was a new series of amplifiers (light weight) there was still a great need for proper a/c and it was a monster at pulling current..I also believe that the camco's front end has a way of monitoring the input current and reducing the output to correspond which would make it hard for alot of folks to do elaborate testing..I will contact Jeff Kuells (dear friend) and see if i can send him a couple of amps for his evaluation that i have intrest in..V-6, PL380,and big lab amp..One of the things i remembered was that the ma 5000 started out strong but after a short time period things changed,subtle but still changed..again thanks for your efforts and keep it up  thanks Randy

[Pascal Pincosy]

Like I said, it was VERY close between all the amps. In fact, on subs no-one could conclusively pick out a winner between the amps, with the exception of the Crest 9200 and maybe the Powersoft K6. In general, I noticed a preference of the Class H amps on tops, with the exception of the 9200. All in all, the PL 380 was right up there with the rest. Interestingly, so was the RMX 4050HD.

I have the PL 380, K6, and FP 10000Q all at my shop right now. I'm going to be fooling around listening to them on my Bassmaxx Trips and my Danley TH-115's this coming Monday night, and Brad Katz from JK Sound will be dropping by with a Crest 9200. I don't think we'll be worrying about the blind testing, as the Crest 9200, which was expected by several of the participants to show the worst results, ended up the winner in the sub category. So my world-view is already upside-down. But I do plan on hitting the subs hard with these amps and seeing if we can find out anything new.

[John Roberts {JR}]

Pascal Pincosy wrote on Sat, 13 October 2007 20:27

So is JR right that there's no difference in sound quality between these amps when they're not in clip or power-limited? The best answer I could give would be "maybe", though in the sub testing, the listeners could pick out the 9200 from any of the others...

I'd like to think that I'm right occasionally but to hedge my bets I didn't say there was no audible difference between "those" amps, only that there shouldn't be a difference between properly designed amps operated linearly.

A perhaps interesting null test just to make propeller heads like me happy would be to drive your speaker bridged but from two different amps at once. Then make a simple resistive summer coming from the two amps. The null could drive a pair of headphones if low impedance resistors or a pair of say 100 K resistors could be fed into an unused amp channel, and listened to. Note: this would also be an excellent way to match gain trims to be equal.

This sum should null if the two outputs are perfectly identical and opposite polarity. If they don't null, you can repeat the test with a handful of amps in different combinations and parse out which amp or amps are the bad actors. Listening to the null will give you a hint at what the error or difference is.

If you get a deep null, don't waste your time listening. there is no difference  

If you don't get a null, why waste your time listening, you can measure what the difference is.

If you really hear a difference, there really is a difference. I have long been suspicious of some kind of subtle tricks in the Crest bass behavior, but not so interested to get one on the bench and check it out. In conversations with JD I never got a definitive reading one way or the other. Whatever the difference is (if any?) appears to be liked by many.  

JR

[Eytan Gidron]

Pascal Pincosy wrote on Sun, 14 October 2007 03:27

There was a definite winner here, and it's not the amp you'd expect to win at all. The Crest Pro 9200 was roundly preferred over any other amp in the testing. The Powersoft K6 took a close second.

Just goes to show you that PR and marketing have major influence on what we think is a good amplifier (or not) and not the actual performance of the amplifier.

I believe that nobody expects the Crest to win because since it was bought by Peavey nobody expects them to come out with a good product. If your test was not a blind test, the Crest 9200 wouldn't score that well.

I'm very interested to see what will be the results of your "high power" tests on Monday.

[Michael 'Bink' Knowles]

Pascal Pincosy wrote on Sat, 13 October 2007 18:27

...the Pro 9200 could still be picked out from the rest of the amps...

I'd be interested in finding out where in the spectrum this amp's difference lies. More high harmonics? Something in the low region? Perhaps you'll let me record the outputs of two for comparison.

-Bink

[Michael 'Bink' Knowles]

I went, I listened, but I didn't record anything--not enough time after my work day to assemble a test package.

Five amplifiers were given a medium-duty workout with a load of one Bassmaxx Trip on one channel, followed by another trial using one Danley TH115 on one channel. The amps sounded very similar, so much so that I concluded any of them would be a fine choice for subs. For source signal we used a techno track for a short time and then switched to TR-909 bass drum beat repeated for consistency. The amps:

Dynacord PowerH 5000
Lab Gruppen FP 10000Q (4 channel)
QSC PL380
Crest Pro 9200
Powersoft K6

Using a horn-loaded subwoofer indoors, working within their linear region (not limiting), matched in output voltage, loaded with a minimum of 2.6 Ohm on only one channel, all these amps sounded virtually the same.

In the early techno track test, the drive level was pushed up until one of the amps displayed a change. The Crest 9200 flashed a limit light first.

We also hooked up a QSC RMX4050HD in bridged mode to see how it held up to the more expensive and more powerful amps and how it handled the Trip. It didn't like having the Trip's 2.6 Ohm load hanging across the two hots while being pushed as hard as the other amplifiers. We had to throttle back on the drive signal to stop some initial horrible clip distortion... after which the listening test made it clear that the RMX bridged for subwoofers wasn't as full in the extreme lows and didn't have the "follow-through" of the other amps. The bridged RMX faded in LF output halfway through each TR-909 kick sample. It wasn't so drastic that the bridged RMX would be an unsatisfactory choice for many casual or budget-limited users, but it was clear that the most discerning PA companies would want to bump up to the next level if they were expecting to supply steady and strong sub power.

As far as a gut-level comparison between the Trip and the TH115; I felt the Danley was more precise and accurate in its portrayal of source signal but the Bassmaxx was more visceral, more "massage", more of a feeling of loudness. When the Danley is very loud it doesn't sound like it. I could see night clubs choosing the Bassmaxx for their dance floors while theaters and HOW would be choosing Danley for realism and linearity.

-Bink

[ProSoundWeb Community]